The ability of a local region of an image or sequence to hide feature information may be referred to herein as “masking.” Quantifying the ability of a local region of an image or sequence to hide feature information has been an ongoing topic of interest in both academic vision research and in the engineering literature, particularly in the fields of watermarking and image/video compression, for which it is generally desirable to modify input sequences in ways that produce no human perceivable visible distortions.
Conventional or typical approaches to masking computations may involve the summing of feature energies (e.g., the squared output of oriented filters) over each local spatial or spatiotemporal region. However, these approaches may tend to generate predictions of high “maskability” (e.g., the ability to achieve masking) in regions near strong edges in the scene. These edges may tend to be highly salient to some (e.g., most) viewers, in a sense that the edges may attract visual fixations that can make it easier for viewers to see the distortions. This can be especially significant where there are uniform image areas near enough to a salient edge to be included within the masking computation's summing region for that edge. As used herein, the terms “salience,” “salient” and the like may relate to a trait or feature of visible, or visually enhancing prominence, conspicuousness, or “standing out,” e.g., from a visually perceivable background.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. Similarly, issues identified with respect to one or more approaches should not assume to have been recognized in any prior art on the basis of this section, unless otherwise indicated.